Printed indicia which are applied to T-shirts and other articles of clothing have become very popular in the last decade. Boutiques which specialize in selling fanciful indicia, such as slogans, college names or sports team names printed on T-shirts and other clothing, are commonly seen in shopping malls. The indicia available at these boutiques can be applied directly to an article of clothing.
Multi-station, turret-type, printing presses are commonly used in the industry to print articles. The printing press of this type has a plurality of flat beds spaced radially along its perimeter. Corresponding to each of these beds is a series of stations whereat the article is either printed or cured. In the prior art, the number of stations employed depended upon the number of colors to be printed. Printing indicia on the articles can consist of ten colors or more for complicated designs. Only one color can be printed per station and printing usually requires some form of curing after each color is printed.
At the initial station of prior printing presses, the article is printed on the flat bed. The bed is typically made of metal such as aluminum or stainless steel. A screen embodying at least a portion of the indicia design to be printed is premade using any conventional means that is well-known in the art. The indicia or design is formed in the screen by a conventional process. The screen has interstices in the places where ink of a particular color is to be deposited onto the article. For each color, a different stencilled screen is used.
To print the indicia onto the article with the colored ink, the article is placed flat on the bed by the operator or an automatic feed. Once printed with the first color, the article must not shift reference or it will be out of registration with the other stations which print the remaining colors. The alignment between the beds and the heads at each station is generally known to one of ordinary skill in the art.
The bed which is carrying the article moves to a station that is set up for printing. After ink of one color is manually placed onto the screen, the colored ink is then flooded onto the screen with a flooder that is connected to a flood bar. The flooder moves across the face of the screen and smears the ink across the screen face in the process. Once the ink is smeared or flooded across the face of the screen, the bed then rises up to the stationary screen with the article sandwiched between the screen embodying the indicia design and the bed carrying the article. A squeegee is then used to squeegee or force the ink through the screen where the indicia design (interstices) exists on the screen. The squeegee performs the squeegeeing function by moving back across the face of the screen in the opposite direction than the flooding. This type of printing on an article is well known in the art. The ink used is also of a type that is well-known in the industry. In addition, the flooders and squeegees used are generally well-known in the art.
After the ink is squeegeed through the screen onto the article, the beds are lowered, and the turret-type press containing the beds is rotated to allow the bed to index to the next station where the ink is again smeared onto the article. Some types of ink require gelling or curing. The ink is cured on the article by any means such as irradiate heating, ultraviolet (UV), or infrared flash curing it to a critical temperature. Heat is commonly applied by a heat curing source directed toward the bed and article. Heat curing can include curing with UV light or infrared (flash curing) which is well-known in the art. The temperature during the curing process must be kept within a window suitable for the ink-curing or gelling conditions, typically around 200.degree. F. The bed, as it is made of metal, tends to act as a heat sink, retaining heat from the successive curing steps. If the temperature of the bed or article is allowed to go too high, the ink has a tendency to scorch or burn, thereby ruining the article and increasing waste and production costs. Furthermore, if the temperature is allowed to go too high, the ink will over-gel, also ruining the article. If the temperature is too low, the ink will not cure properly, and will not adhere to the article and may adhere to the screen at the next print station. The ink on the article must also be cured and dried uniformly. If it is not, there will be irregularities and the ink will have a tendency to peel off of the article at the irregularities. The above printing process is repeated several times, depending on the number of colors required, in a sequence that is programmed by a user into an operator panel.
Using inks which require curing typically requires a curing station for each printing station. The curing station would be located adjacent to each printing station. This takes up valuable space in a production facility by requiring presses to have double the number of stations as colors, if curing is required for each color used. It may also require the purchase of multiple curing units, one for each printing station on some types of printing presses.
One prior printing press configuration has included the previously listed features as well as further details that limit an operator in programming how the sequencing will take place. In order to fully explain the sequence programming of the previous printing press, a description of one embodiment of a known printing press will follow. This system comprises a multi-station, turret-type printing press. The printing press is of a type conventional in the art. The printing press consists of a series of beds spaced along its perimeter radiating outward from its center. The beds can be made of metal such as aluminum or steel. Corresponding to the beds are a series of stations. The stations are designed to imprint articles with ink. The construction of print stations are generally known in the art and typically consist of a flood bar with flooder and squeegee bar with squeegee arrangement. In the center of the press is a conventional motor or valve assembly to rotate and index the beds between the stations. The previous press also has a loading station and an unloading station.
During operation, the turret-type press rotates in a single direction, usually counterclockwise. The general operation of the turret-type press is well-known in the art. A separate curing unit is placed at the unload station of the printing press. The curing unit is preferably a flash curing unit. Flash curing units are well-known in the art and flash the article with infrared light.
The prior sequencing system of the previous printing press limits the operator selecting which print stations will be used to perform the printing task at hand and in what sequence they will operate. The operator is also limited in the automatic and manual control of curing the ink on the article to be printed after each printing step when desired.
Operation of one prior sequencing system of a previous printing press is disclosed in FIGS. 1 through 15. FIGS. 1 through 15 are flow charts of the previous printing press control program that runs on a controller, and it will be explained below along with the necessary structure. Several problems and disadvantages exist with this previous control program and structure. FIG. 1 begins with the control program allowing the operator or user to delete or modify the operator program. If the old program is not deleted or modified, the operator program previously entered begins to run. If the operator wants to change the operator program, the control program allows the operator to modify one or more cycles within the operator program (job). A cycle is one revolution of the beds around the printing press while remembering that the printing press can only rotate in one direction. The previous printing press allowed a user to enter up to eleven cycles in the operator program (job) on a printing press with eight total stations. However, one significant problem with the previous printing press is that only one operator program could be stored in the controller at one time. Thus, if an operator needed to make dramatic changes in the operator program for automated control, the operator would effectively have to re-program the controller each time the operator program needed to be changed. This is significant because re-programming takes up valuable run time which could otherwise be used for printing items.
Continuing with FIG. 1, if a user wanted to erase the old job, the heads (stations) stored as active and the heads printing in double mode in the old operator program were reset. If the old program was not erased or a new job was to be entered, a rotatable thumbwheel was used to set which cycle number was to be changed or added. For that cycle number, each head (station) is set to either active or inactive, and these states are stored in random access memory.
Next, for each cycle and each head in each cycle in the prior sequencing system, the heads need to individually be set for printing in single or double print mode, single print mode being one flood stroke with one squeegee stroke, and double print mode being one flood stroke with one squeegee stroke and then another flood stroke with another squeegee stroke. In order to set these states for printing heads (stations) for each head and cycle, single/double/off switches are provided for each head on an operator control panel. However, there is no means provided to switch the curing heads to inactive without re-entry of the operator program (job). This is another significant problem with the previous printing press. Specifically, when an operator is running the printing press in automatic (revolver) mode and the operator wants to deactivate a curing station that has been set up as an active head (station), the operator cannot deactivate the curing head without reprogramming the entire job. Thus, valuable production time is lost during this down time and makes the prior printing press design more costly to run and less efficient. In addition, a further disadvantage with the prior sequencing system is that the flash cure information was not stored in battery backup locations. Thus, every time the printing press was powered down, the information for which heads were set up as flash cure heads was lost and the operator needed to reprogram this information. This took time and kept the printing press off-line and was a significant disadvantage with the owners and users.
The programming of the heads being active or inactive for printing, and printing in single or double mode is completed in FIG. 2. Thereafter, the operator must program whether the flash cure at the unload station (revolver flash) is active for each cycle. Operator programming either then continues with more cycles and head configuration for printing, or the operator sets up the heads that will operate as flash cure heads (besides the revolver flash). This set up sequence contributes to the previously mentioned problems with turning of a flash cure head during automated operation and is a significant disadvantage because the old program does not allow the operator to turn off a flash cure unit without reprogramming the cycle.
FIG. 3 depicts the prior sequence with the control program taking the operator program (job) and running it upon startup by an operator. The control program was set to run the first cycle and the even cycle register in memory was set to odd for later use. The information for the present cycle was then moved from its normal position in RAM (random access memory) to a global position in RAM. This information included heads (stations) active in the present cycle and the heads that were printing in double mode. Once the information of the present cycle was stored in the global (GBL) RAM area, the cycle number was incremented by one in a cycle register (memory).
Referring to FIG. 4 of the prior sequencing system, a general check for the status of the cycles is performed. If there are no active heads in the next cycle, the present cycle is the last cycle. If this is the case, and the present cycle is half over, and audible alarm is sounded to notify the operator to come back to the printing press for unloading. The lap counter is the position of the beds within a cycle relative to where the beds started at the beginning of that cycle. For a printing press that contained ten stations, one full lap would equal a lap counter value of ten. The revolver flash is then put into a buffer register for the revolver flash later in the sequence.
As previously mentioned, an even cycle register existed to check the even/odd status of the present cycle. This will now be explained. Referring additionally to FIG. 38 (the present invention), a similar buffer and register configuration from the previous printing press design is used. A first buffer BR1 (even cycle buffer) and a second buffer BR2 (odd cycle buffer) are disclosed for storing the information for the even and odd cycles, respectively. A shift register is used to keep track of the position of the beds during each of the cycles (lap counter value in relation to bed position). As FIG. 4 discloses, if the cycle is odd, the active/inactive head information for the present cycle will be placed into BR1. Likewise, if the cycle is even, the active/inactive head information for the present cycle will be placed into BR2.
Thus, information for two cycles will be in BR1 and BR2 for the circumstance when some of the heads are operating within one cycle while the other heads are operating within another cycle. It is easily understood that not more than two cycles will be operating at the same time. These buffers and register will be described in further detail below.
Referring to FIG. 5, an emergency stop button will be continuously checked along with a safety circuit along the perimeter of the printing press. If there is an indication of these safety features not being in the safe condition, the machine will stop and an alarm indicator will appear on the operator control panel. An index on proximity switch (detector), which is well known in the art, existed on the base structure to check if the beds were positioned correctly underneath the heads or stations and to check if the beds were in the down position. If not, then a timer waited until the correct alignment existed or it would time out into an alarm mode. If the correct rotation alignment existed, then an index off proximity switch is checked to see the indexing valve is in the correct position. If the index off proximity switch was off, then a timer starts which would time out into alarm mode if enough time passes without the beds moving to the down position. Once the alignment in both the rotational and vertical orientation is correct, the beds are indexed by turning the index on valve on which rotates the beds in one (usually counter-clockwise) direction.
Referring to FIG. 6 of the prior system, the shift register is then shifted right to keep track of the position of the beds within the cycles currently placed into the buffer registers BR1, BR2. Next, the control program checks which of the heads (stations) are set up in the operator program to operate as double print mode. Double print mode strokes the flood bar, strokes the squeegee, and then repeats the flood and squeegee again. Double print mode heads will create head counter values of two and non-double print mode heads will create head counter values of one for either single print mode heads or curing heads. Once the head counters are set to their respective values, a one is then placed into the eighth pallet position (the pallet which first started in the loading station) to keep track of the positions of the pallets or beds for the relevant cycles (see FIG. 38). The eighth pallet position register (shift register pallet) location used will depend on whether the current cycle is an odd cycle or an even cycle. If even, the eighth prime shift register pallet will be set to one. If odd, the eighth shift register pallet will be set to one. The lap counter is then incremented by one to keep track of the position of the bed (pallet) wheel around the printing press for the current cycle.
Referring to FIG. 7 of the prior system, the checks for each head begin and an additional major problem with the previous printing press sequencing system is realized. Specifically, head one cannot operate as a curing station and the flow chart does not include such a curing operation. Likewise, as will be described below, the last head cannot operate as a flash cure station either. A check of whether the first head is active is performed by checking position one of the shift register and the two buffer registers. If the head is active, and the counter for head one is not zero and head one is set up as single or double print mode, then a flood stroke is performed for head one and ink is flooded over the silk screen. One additional problem with the prior system is that only one proximity switch is provided for each head. Specifically, a proximity switch (detector) is placed on the head portion of each head, and metal contacts were placed at each end of the stroke. Only providing one proximity switch limited the operator in the size of design being printed on the items. Specifically, a user could not change the length of the stroke when only one proximity switch was used. This significantly limited the operator and/or owner in the types of designs that could be created on the press. Thus, as disclosed at the bottom of FIG. 7, the proximity switch will indicate the end of the flood stroke, but will not allow the stroke length to be changed, a significant disadvantage of the prior system. A timer would create an alarm condition upon timeout.
Referring to FIG. 8 of the prior system, a head two active/inactive check is performed. If head two is active and the head two counter is not zero, either flooding of ink across the silk screen will occur, or one of several error conditions will occur. Alternatively, if the head is not active, flash curing will occur if flash curing is set for head two. Thus, a previously mentioned problem is encountered. Flash curing will always take place if the head is set up to operate as a flash curing unit. No manual override can prevent the flash curing at the head. The operator must stop the printing press to re-program the job without the head operating as a curing head. Similar checks for alarm conditions and the end of the flood stroke are performed for head one as for head two.
Heads three through seven operate the same as head two as FIG. 9 denotes with a broken line for these stations. FIG. 9 also discloses a previously mentioned problem of the last head not being capable of operating as a curing head. The operation of head eight is, thus, similar to the operation of head one.
FIG. 10 first discloses the operation of a curing station at the unload station (revolver flash curing station). When the control panel flash on/off switch is on, the revolver flash will be set on if the buffer and register values indicate an active value. Once the revolver curing is checked, indexing up is checked. If the proximity switch for revolutions (index on proximity switch/detector) is on (the beds are properly underneath the heads), the table or bed wheel is then lifted into the up position. When the up/down proximity switch/detector is on, the indexing cylinder which rotates the bed wheel is brought back to receive the next bearing underneath the next pallet or bed on the bed wheel. Error time alarms were also provided. The printing press sequencing was now ready for the squeegee operation.
FIG. 11 of the prior system begins by again checking if head one is active. If head one is active and the head counter for head one is not zero, and head one is on, then the flooder is raised, the squeegee is lowered, and the squeegee then moves across the face of the silk screen to press the ink through the interstices within the screen and onto the item. When the squeegee is at the end of the stroke (the proximity switch is on), the squeegee is then lifted off of the silk screen. A time out alarm is again provided for the proximity switch. Again, head one cannot operate as a flash cure station in the previous printing press.
FIG. 12 of the prior system discloses the squeegee or curing operation for head two. If head two is active and head two counter is not zero, the squeegee operation will take place as in FIG. 12 if head two is on. Otherwise the system will move onto the next head or go into one of several error modes. Heads three though seven then operate the same as head two.
FIG. 13 of the prior system discloses the operation of head eight, which was the same as the operation of head one. The control program checks if revolver curing station (unloading station) is being operated and checks if it had completed or if an alarm or stop had been received by the controller within FIG. 14 of the prior system. Indexing was then continued by checking if the index off proximity switch is on (the correct position of the indexing cylinder).
Referring to FIG. 15 of the prior system, if the up/down proximity switch was on, then the bed wheel or table was lowered and all of the head counters were decremented by one. If any one of the head counters was greater than one at this point, at least one of the heads was set up as double print mode and another flooding and squeegeeing operation was needed to be performed for those heads. The table would then be raised for those double print heads before the strokes occur. If all head counters were zero, printing complete for this position, the lap counter was then checked to see if the cycle was over. If the lap counter was less than ten and the system was still set on automatic mode, the system then began the next position within the current cycle. Otherwise, if the counter was equal to ten, the present cycle was complete and the active heads were reset for the present cycle. The even cycle on was then set odd if even and set even if odd for movement of the appropriate cycle information into the appropriate buffer register as the flow chart disclosed in conjunction with FIG. 38. The sequencing then continued on. For short multi-color production runs, automatic presses are not necessarily the most efficient means of production. Short production runs are often made using manual presses. Manual presses have their own problems. Manual presses are very labor-intensive and require large amounts of setup time. To set up manual presses also requires a highly trained individual. Each screen must be put in registration separately. Each color may be printed on separate manual presses requiring purchase of many presses. Individual manual stations take up valuable floor space. A manual configuration also requires multiple flash or ink curing units. Thus, valuable time is wasted waiting for the screen and ink to cool.
An additional disadvantage of the prior system is that every time the printing press was shut down, the heads would always return to the inner or rear position. Not only the printing heads would return to the rear position, but the curing heads would return or be positioned at the rear position. The flash curing stations typically operate at temperatures upward of 200.degree. F. Thus, when the press was powered down, a potential fire hazard existed or at least heat damage would occur to the pallets because the flash curing unit would be sequenced over the pallet instead of in the front position. The sequencing system of the present invention solves these, the previously mentioned, and other problems.